package Text;

import java.util.LinkedList;

public class MyLinkedList {

        static class ListNode{
            public int val;
            public ListNode next;
            public ListNode prev;
            public ListNode(int val){
                this.val=val;
        }
        }
    public ListNode head;
    public ListNode last;

    //头插法
    public void addFirst(int data) {
        ListNode node = new ListNode(data);
        if (head == null) {
            last = head = node;
        } else {
            node.next = head;
            head.prev = node;
            head = node;
        }
    }
    //尾插法
    public void addLast(int data){
        ListNode node =new ListNode(data);
        if(head==null){
            head=last=node;
        }
        else{
            node.prev=last;
            last.next=node;
            last=node;
        }
    }
    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){
        try {
            CheckIndex(index);
        }catch (IndexNOTExecption e){
            e.printStackTrace();
        }
        ListNode node=new ListNode(data);
        if(index==0){
            addFirst(data);
            return;
        }
        if(index==size()){
            addLast(data);
            return;
        }
        ListNode cur=findIndex(index);
        node.next=cur;
        cur.prev.next=node;
        node.prev=cur.prev;
        cur.prev=node;


    }
    private void CheckIndex(int index){
        if(index<0||index>size()){
            throw new IndexNOTExecption("index位置不合法");
        }
    }
    private ListNode findIndex(int index){
        ListNode cur=head;
        while (index!=0){
            cur=cur.next;
            index--;
        }
        return cur;
    }
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode cur=head;
        while(cur!=null){
           if(cur.val==key){
               return true;
           }
            cur=cur.next;
        }
        return false;
    }
    //删除第一次出现关键字为key的节点
    public void remove(int key) {
        ListNode cur = head;
        while (cur != null) {
            if (cur.val == key) {
                if (cur == head) {
                    head = head.next;
                    if(head!=null){
                        head.prev = null;
                    }else{
                        last=null;
                    }

                } else {

                    if (cur.next == null) {
                        cur.prev.next = cur.next;
                        last = last.prev;
                    } else {
                        cur.prev.next = cur.next;
                        cur.next.prev = cur.prev;
                        return;
                    }
                }

            }
            cur=cur.next;
        }
    }
    //删除所有值为key的节点
    public void removeAllKey(int key){
        ListNode cur = head;
        while (cur != null) {
            if (cur.val == key) {
                if (cur == head) {
                    head = head.next;
                    if(head!=null){
                        head.prev = null;
                    }else{
                        last=null;
                    }

                } else {

                    if (cur.next == null) {
                        cur.prev.next = cur.next;
                        last = last.prev;
                    } else {
                        cur.prev.next = cur.next;
                        cur.next.prev = cur.prev;

                    }
                }

            }
            cur=cur.next;
        }
    }

    //得到单链表的长度
    public int size(){
        ListNode cur=head;
        int count =0;
        while(cur!=null){
            count++;
            cur=cur.next;
        }
        return  count;
    }
    public void display(){
        ListNode cur=head;
        while(cur!=null){
            System.out.print(cur.val+"  ");
            cur=cur.next;
        }
    }
    public void clear(){
        head=null;
        last=null;
    }
}
